caliper change - plugging brake line, to reduce loss/air in system/ease bleeding

Whenever I have replaced a caliper, I prefer not to clamp the hose, and just either collect what drips, or use a work glove and a zip tie for if its going to be off for longer.

If you are going to bleed the system afterwards, should not be an issue :)

Kenai said:
This is the sort of post that makes you feel really good about the fact people are allowed to DIY service safety critical elements of cars like the brakes :p
Click to expand...

I feel like you would be even less happy if you ever spent any time in a commercial garage :D
 
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The main concern about bleeding (beyond our vatican statues) would be if the ABS unit gets air in it -
whilst I think older BMW units don't need OBD stimulation to run the ABS motor , newer units do I believe, like VAG.
I thought all the solenoids are open/free-flowing under normal operation (fail safe if power failure) so not sure why air maybe an issue.


At a minimum probably need to do a test drive and try the ABS, to avoid surprises in the field.


[
ski pole to prop the brake pedal seems to work ..
just inspected a new Halfords professional flare spanner 10/12 right .. next to an older used williams 11/13
where is this junk made .. are they forged ? look at the imperfections on the jaw face , I'm afraid it could knack a flare nut; does their lifetime guarantee reimburse me for that.


junk.jpg

]
 
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I really don’t want to seem to be giving you grief, but you’re way way way over thinking a simple process.
I use a brake pedal depressor every day, but only to check the hoses for bulging etc when under pressure.
There’s zero reason to use one when replacing a caliper.
 
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In a professional situation bleeding is quick I imagine - you have car on lift/sills and whipped all 4 wheels off (I usually just have one wheel at a time !)
plus a pro bleeder, with large capacity, so greater fluid loss is less of an issue ... what do you use ?

How do you check any air in ABS system ?
 
jpaul said:
In a professional situation bleeding is quick I imagine - you have car on lift/sills and whipped all 4 wheels off (I usually just have one wheel at a time !)
plus a pro bleeder, with large capacity, so greater fluid loss is less of an issue ... what do you use ?

How do you check any air in ABS system ?
Click to expand...
to be honest with you I struggle to see how abs system is going to get air in it, the pump is usually higher up in the bay so unless you mess with that or leave reservour empty, it shouldn't suck any air "up" the system. Realistically if you're super lazy you can just gravity bleed.

fluid runs down to the lowest part of the car.. so just reinstall the caliper, overfill the brake fluid reservour and open the bleed nipple. gravity will do the rest - in theory, I've had 50/50 success with it.


I use a vacuum system like this - https://www.amazon.co.uk/Laser-Tools-8018-Vacuum-Tester/dp/B08LZSD3W3/ref=sr_1_16?crid=20DXPJ85P4GQE&dib=eyJ2IjoiMSJ9.jQtLcdKeBNQ3cRGethGv5tqPuooIl5r2EcK_3sUUsCJSWrgwezcjN0dHWT2zREsgcB5yUIEvlXgxicMz-YoR22WtnZMI9mmdL3OU9NoOwRXqTFCvJAQNvrDeqUMfwG0Qg_m-bYuZzCTMczrCMZ76VQNa45fvr9j9CnuSMh7hbGP6iuGUL3aWAWy64J_w0BUONlrwwSAmpYvVfNzTD4tLZNzTkrlq132F7axlVJGrnMOWm0GxO3mUooH9KoY5__0qtpFRH2w1jWIgWXH8l1aIz3JyufvHai7jRo9K9hdm2is.o7nU8iNlCNadv9lFtQaN5fpUi1zsJxn-8IwZykQ_kNk&dib_tag=se&keywords=brake+bleed+vacuum+pump&nsdOptOutParam=true&qid=1729112378&sprefix=brake+bleed+vacuum+,aps,72&sr=8-16

mixed results from reviews but I had no issues and bled my system multiple times.
 
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jpaul said:
In a professional situation bleeding is quick I imagine - you have car on lift/sills and whipped all 4 wheels off (I usually just have one wheel at a time !)
plus a pro bleeder, with large capacity, so greater fluid loss is less of an issue ... what do you use ?

How do you check any air in ABS system ?
Click to expand...
Just whip off each corner at a time and do the work. JFDI.

Then bleed the brakes with key at ignition 1 and starting furthest from the ABS modulator.

That’s it, IF you have any problems after that go into diagnosis mode. This theorising, as ever, is just painful.
 
grudas said:
to be honest with you I struggle to see how abs system is going to get air in it, the pump is usually higher up in the bay so unless you mess with that or leave reservour empty, it shouldn't suck any air "up" the system.
Click to expand...
This.
You would have to do something monumentally daft to introduce air into the abs unit.
jpaul said:
In a professional situation bleeding is quick I imagine - you have car on lift/sills and whipped all 4 wheels off (I usually just have one wheel at a time !)
plus a pro bleeder, with large capacity, so greater fluid loss is less of an issue ... what do you use ?
Click to expand...
The last 2 dealers I worked at use these..

www.rozone.co.uk

S15 Brake Bleeder

The Romess S15 is a solid mobile brake maintenance unit designed for service centres with a mid to high number of brake fluid changes per day. Order now.
www.rozone.co.uk www.rozone.co.uk

Obviously overkill for home use, but for speed, this is just the job.
 
JonRGV250 said:
This.
You would have to do something monumentally daft to introduce air into the abs unit.
Click to expand...

I've done it before, on a motorcycle.

The front caliper was a bit seized so I took it off to clean it all and replace the seals and pistons.

I didn't even think about the fact it had ABS as I'd never owned a motorcycle with it before. Anyway just left the hose open for it to bleed out.

I put everything back and there was literally no pressure in the system at all, however I got a pro tip.

Basically just put a bungee cord around the brake lever, left it a few days, then pump the lever a few times, tie it up again, wait a few days, repeat. After about 4-5 days the system sorted itself out and was fine.

I'm guessing pressuring everything forced the air to the top.
 
sounds like if the ABS system had air you'd always get a soft pedal, even without having to test ABS

BUDFORCE said:
Basically just put a bungee cord around the brake lever, left it a few days, then pump the lever a few times, tie it up again, wait a few days, repeat. After about 4-5 days the system sorted itself out and was fine.
Click to expand...
so you had to hold up the pedal ... and the air eventually migrated into the reservoir ? versus usual bleeding where you are hoping air is pushed out along with pressurized fluid

I guess abs units are designed without intentional pockets in the roof of the device that might trap air.
 
jpaul said:
so you had to hold up the pedal ... and the air eventually migrated into the reservoir ? versus usual bleeding where you are hoping air is pushed out along with pressurized fluid

I guess abs units are designed without intentional pockets in the roof of the device that might trap air.
Click to expand...


It was a motorcycle so lever (front brake lever) but basically yes.

I'm not actually sure what process went on, I'm guessing (stress guessing) that as it was under pressure, the air transferred through the liquid, slowly, and ended up at the highest point being the reservoir.

Whatever the science, it worked.
 
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